Shoe stiffener means and method

ABSTRACT

BINE THE SHOE UPPER MATERIAL AND THE SHOE INNER LAYER IN A SANDWICH WHICH CAN BE LASTED AS TO FORM A BOX TOE IN A SHOE UPPER. THE NOVEL STIFFENER BLANKS PREFERABLY HAVE SUBSTANTIALLY UNIFORM THICKNESS AT ALL BUT A MARGINAL EDGE PORTION WHICH IS SKIVED.   AN INTEGRAL, UNSUPPORTED, PREFORMED THERMOPLASTIC FILM STIFFENER FOR A SHOE UPPER IS FORMED BY MOLDING A THERMOPLASTIC SHOE STIFFENER BLANK ON A RELEASE SURFACE WITH SAID STIFFENER BLANK DEFINING A SKIVED EDGE AND REMOVING THE THERMOPLASTIC SHOE STIFFENER BLANK FROM THE RELEASE SURFACE. THE SHOE STIFFENER BLANK CAN THEN BE POSITIONED BETWEEN A SHOE UPPER MATERIAL AND A SHOE INNER LAYER WHEREUPON THE STIFFENER BLANK IS ADHERED BY HEAT AND PRESSURE TO COM-

July 11, 1972 W- E. PALM. JR

SHOE STIFFENER MEANS AND METHOD Filed 001;. 17, 1969 United States Patent US. Cl. 156-249 1 Claim ABSTRACT OF THE DISCLOSURE An integral, unsupported, preformed thermoplastic film stiffener for a shoe upper is formed by molding a thermoplastic shoe stiffener blank on a release surface with said stiffener blank defining a skived edge and removing the thermoplastic shoe stiffener blank from the release surface. The shoe stiffener blank can then be positioned between a shoe upper material and a shoe inner layer whereupon the stiffener blank is adhered by heat and pressure to combine the shoe upper material and the shoe inner layer in a sandwich which can be lasted as to form a box toe in a shoe upper. The novel stiffener blanks preferably have substantially uniform thickness at all but a marginal edge portion which is skived.

BACKGROUND OF THE INVENTION Many different types of shoe stitfeners such as box toe blanks and counter blanks are known in the shoe industry. The stiffeners are used between a shoe upper and shoe inner layer as in box toe constructions to provide support for a shoe upper and stiffen it in use. The box toe blanks are often formed as thermoplastic impregnated textiles. Production of such box toe blanks often involves impregnating steps as well as cutting and skiving steps which increase cost of the box toe blanks. In one method of forming box toe stiffeners, a molten thermoplastic material is applied directly to a shoe upper in molten form after which the upper is lasted to form a box toe structure. This method which can be carried out by the use of a machine is described in US. Pat. No. 3,277,867 issued Oct. 11, 1966 has certain drawbacks. For example, application of a molten thermoplastic material to a shoe upper can cause problems of uniformity of thickness, particularly where there are irregularities in the shoe upper such as overlays, stitching, cup vamps and the like. Moreover, bubbling of the molten thermoplastc material when applied can occur which creates unwanted irregularities and causes problems in lasting. Care must be taken in applying the molten thermoplastic to prevent strike-through, i.e., passing through of the thermoplastic to either the surface of the shoe upper or lining.

It is an object of this invention to provide a novel and advantageous method of forming shoe stiffener blanks.

Another object of this invention is to provide a method in accordance with the preceding object wherein said shoe stiffener blanks can be stored and transported prior to use.

Still another object of this invention is to provide a method in accordance with the preceding objects and further including formation of a laminate of a shoe upper, shoe stiffener and shoe inner layer suitable for lasting.

Still another object of this invention is to provide a novel and advantageous shoe stiffener blank which can be formed in a single operation with a skived edge.

BRIEF DESCRIPTION OF THE INVENTION According to the invention, a thermoplastic stiffener blank for a shoe upper is formed by molding an unsupported thermoplastic shoe stiffener blank on a release surface with the stilfener blank defining a skived edge. The thermoplastic shoe stiffener blank is then removed from the relase surface and can be stored, transported and/or immediately used in a box toe or shoe stiffening operation.

3,676,250 Patented July 11, 1972 Preferably the shoe stiffener formed is positioned between the shoe upper material and a shoe inner layer after which it is adhered to the shoe upper material with the use of heat and pressure.

Novel thermoplastic stiffener blanks compromise an unsupported film of thermoplastic material defining a preformed configuration suitable for use as a shoe stiffener such as a shoe counter blank or a shoe box toe blank. The film preferably has substantially uniform thickness at all but a marginal edge portion thereof which is feathered or skived. The thermoplastic material is capable of being heat and pressure activated preferably at a temperature in the range of from 250 F. to 500 F. to laminate a shoe upper material and shoe lining material therewith.

It is a. feature of this invention that a single forming step is used to form an unsupported, film shoe stiffener blank with a skived edge suitable for use in forming box toe shoe configurations. The method can be used with all types of shoe uppers even where irregularities are present in the shoe upper adjacent the shoe stiffener blanks. Problems of bubbling and irregularities are avoided. No subsequent skiving operation is necessary.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will be better understood from the following specification when read in conjunction with the accompanying drawings in which:

FIG. 1 is a top plan view illustrating a box toe blank formed on a release surface in accordance with a preferred method of this invention; and

FIG. 2 is a side view thereof showing a subsequent step in the method of this invention.

DESCRIPTION OF PREFERRED EMBODIMENTS With reference now to the drawings, a preferred embodiment of a premolded thermoplastic shoe stiffener blank in the form of a thermoplastic box toe shoe blank is illustrated at 10 in FIG. 1 formed on a release surface 11. The box toe blank 10 has an outer configuration defined by curved edge 12 and straight edge 13 suitable for use in forming a box toe in a shoe product as conventionally known in the art. The main body portion 14 of the blank 10 is in the form of an unsupported film having uniform thickness preferably in the range of from 0.005 inch to 0.090 inch. Thus, no textile or other support layers need be used and the blank is preferably homogeneous throughout its mass. An integral skived marginal portion 15 preferably has a width of no more than about 0.5 inchand tapers downwardly to a substantially line edge 13.

The thermoplastic material of the shoe stiffener 10 is preferably a synthetic polymeric material which can be heat and pressure activated to adhere to conventional shoe upper materials at temperatures in the range of 250 F. to 500 F. and at pressures in the range of from 300 p.s.i. to p.s.i. The thermoplastic material has good stiffening properties under normal environmental conditions to support a shoe box toe in a predetermined three-dimensional configuration. Suitable thermoplastic materials for use in this invention are commonly used in the box toe art in laminated or impregnated box toe blanks and include various polyesters and copolyesters, polyamides, polyesteramides and polyvinyl compounds including but not limited to linear copolyesters of terephthalic acid, isophthalic acid, adipic acid and sebacic acid or other diabasic acids with a glycol such as ethylene glycol and 1-4 butane diol. Polyolefins such as polyethylene, polypropylene can also be used as can ethylene vinyl acetates and the like.

Preferably the thermoplastic shoe stiffener blanks, which may be box toe blanks or counter blanks, are molded directly into the exact configuration desired for usage so that no cutting out or later operations need be performed prior to usage to laminate a shoe upper to a shoe inner layer. Conventional forming or molding apparatus and methods can be used to form the blank 10.

The thermoplastic shoe stiffening blank is molded in a single operation on a fiat release surface 11 in a configuration suitable for use as a box toe directly without any need for subsequent skiving, shaping, cutting out or other procedures. The release surface 11 forms one side of the mold for the thermoplastic stiffener blank. The release surface 11 is rigid and preferably composed of polytetrafluoroethylene or a polytetrafluoroethylene release coating although other release surfaces such as Kel-F, glass and the like can be used so long as their non-stick properties are suitable to allow ease of removal of the blanks formed. The molding step is preferably carried out at a temperature in the range of 300 F. to 500 F. with the blank 10 being applied as a heated, molten plastic to the release coating and then solidified by cooling to form the blank 10 in its final configuration including the integral skived marginal portion 15. The molding can be carried out by conventional molding equipment such as the apparatus described in U.S. Pat. No. 3,277,867. After molding of the blank 10, it is removed from the release surface 11 and can be stored, transported or used directly to combine a shoe upper and shoe inner layer. The blank 10 has sufiicient resiliency and stiffness to be self-supporting as a flat film even after removal from the release surface.

Conventional shoe upper materials such as canvas, leather, vinyls, synthetic shoe uppers and synthetic leathers can be stiffened by the shoe stiffener blanks of this invention. Similarly, conventional shoe inner layers such as shoe linings formed of leather, vinyl, foam vinyl, knitted and woven textiles and the like can be laminated to shoe uppers with the interposed, sandwiched shoe stiffener blanks of this invention.

Preferably the laminating step is carried out by positioning the blank 10 between a shoe upper and shoe lining whereupon the resulting sandwich is pressed and heated in conventional box toe or counter machine to form a laminate. The lamination is preferably carried out at temperatures in the range of from 250 F. to 500 F. and at pressures of from 30 lbs. to 80 lbs. p.s.i. with dwell times of from 2 to 10 seconds. However, the times, temperatures and pressures can vary considerably depending upon the particular materials used and the thicknesses of the layers used.

After a stiffened laminate of the shoe upper, shoe stiffener and shoe inner layer is formed, the laminate can be lasted in lasting machines to form finished box toe shoe products.

In a specific example of this invention, a rigid polytetrafluoroethylene planar surface 11 is used in conjunction with a conventional box toe applying machine produced by United Shoe Machinery Corporation Model B constructed in accordance with U.S. Pat. No. 3,277,867. The thermoplastic material used to form the pre-molded box toe blank 10 is a mixture of 80% by weight Berselon No. 1109, a trademarked product produced by General Mills Inc. of Minneapolis, Minn., a polyamide-type resin, and 20% by weight of the mixture of Berselon No. 1300, a trademarked product produced by General Mills Inc. of Minneapolis, Minn., a polyamide-type resin, along with 1 part by weight of the two resins used of Acrowax C produced by Glyco Chemical Inc. of Chicago, Ill. The materials are uniformly blended at a temperature of about 350 F. and then cooled and pellets formed. The thermoplastic mixture is fed to the applying machine and the machine melts the mixture at a temperature of approximately 320 F. with the setting of the machine maintained at applier 310-330 F. melt unit 320 F.-350 F. Sulficient material was deposited on the polytetrafiuoroethylene surface to produce a pre-molded box toe blank 10 having dimensions such that the thickness was uniformly 0.027 inch with the feathered edge tapering substantially to line thickness and having a width of approximately 0.5 inch. The width of the box toe along the feathered edge was 3% inches and the maximum length of the box toe was 4 inches.

After applying the material to the polytetrafluoroethylene surface, it was allowed to cool for 16 seconds at standard room temperature after which it was found to be in a hardened solidified form.

The box toe blank 10 thus formed was removed from the polytetrafluoroethylene surface merely by lifting an edge as illustrated in FIG. 2. The blank 10 was than sandwiched between an upper layer of calf skin leather having a thickness of 0.015 inch and a lower layer of nylon tricote woven material having a thickness of 0.010 inch. The uncombined laminate was then placed into a heated press and laminated to form a combined material suitable for lasting. Lamination was carried out at a temperature of 375 F. with a dwell time of 7 seconds and a pressure of 60 p.s.i. No strike-through occurred. The resulting laminate was then lasted at a temperature of approximately F. after steaming in a conventional lasting machine to form an excellent box toe in a shoe upper.

While a specific example has been shown and described, many modifications are possible. For example, while it is preferred to laminate the shoe upper to the shoe lining while the materials are flat, in some cases, the shoe stiffener can be interposed between the shoe upper and shoe lining and lamination accomplished by combining in a curved configuration.

What is claimed is:

1. The method of stiffening the forepart of an upper at the toe, said forepart embodying an outer material and a lining material, comprising forming on a flat, uniformly smooth release surface a box toe blank, said blank being comprised of a homogeneous unreinforced film of thermoplastic sheet material, applied thereto in molten condition and allowed to become solid, said blank comprising an area coextensive with the area of the forepart of the upper at the toe to which it is to be applied and being defined by a straight edge corresponding in length to the transverse width of the toe, said edge being skived, and a curved edge corresponding in length to the peripheral edge of the upper at the toe, manually stripping the solid uniformly fiat film of thermoplastic from the release surface preparatory to use in an upper for reinforcing purposes, assemblying the unitary blank between the upper material and the lining material of the upper at the toe, elfecting lamination of the blank with the upper and lining material by subjecting the composite structure to heat and pressure in a press, said lamination being carried out at a temperature of approximately 375 F. at a pressure of 60 p.s.i. for a period of approximately 7 seconds to form a composite structure wherein there is no strikethrough of the thermoplastic of the blank with no substantial dimunition in the unitary thickness of the blank, following lamination steaming the laminated portion of the upper and then lasting the steamed upper at a temperature of approximately 175 F.

References Cited UNITED STATES PATENTS 2,052,579 9/1936 Muir 156-231 X 3,115,651 12/1963 Kamborian 12-146 D 3,174,236 3/1965 Field 12-146 D X 3,183,290 5/1965 Guarnieri et al. 264-3 16 X 3,277,867 10/1966 Kilham et al 118-204 3,305,618 2/1967 Sucher et a1. 264-316 3,316,573 5/1967 Chaplick et a]. 12-146 D CARL D. QUAR-FORTH, Primary Examiner R. S. GAITHER, Assistant Examiner U.S. Cl. X.R. 

